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From: Roberto Sassu <roberto.sassu@huawei.com>
To: <jarkko.sakkinen@linux.intel.com>, <zohar@linux.ibm.com>
Cc: <linux-integrity@vger.kernel.org>,
	<linux-security-module@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <silviu.vlasceanu@huawei.com>,
	Roberto Sassu <roberto.sassu@huawei.com>
Subject: [PATCH v3 5/5] tpm: ensure that output of PCR read contains the correct digest size
Date: Tue, 30 Oct 2018 16:47:11 +0100	[thread overview]
Message-ID: <20181030154711.2782-6-roberto.sassu@huawei.com> (raw)
In-Reply-To: <20181030154711.2782-1-roberto.sassu@huawei.com>

This patch ensures that the digest size returned by the TPM during a PCR
read matches the size of the algorithm passed as argument to
tpm2_pcr_read(). The check is performed after information about the PCR
banks has been retrieved.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 8e821e7b4674..477dcc30fc53 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
 int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
 		  struct tpm_digest *digest_struct, u16 *digest_size_ptr)
 {
+	int i;
 	int rc;
 	struct tpm_buf buf;
 	struct tpm2_pcr_read_out *out;
 	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
 	u16 digest_size;
+	u16 expected_digest_size = 0;
 
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
+	if (!digest_size_ptr) {
+		for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
+		     chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
+			;
+
+		if (i == ARRAY_SIZE(chip->active_banks))
+			return -EINVAL;
+
+		expected_digest_size = chip->active_banks[i].digest_size;
+	}
+
 	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 	if (rc)
 		return rc;
@@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
 
 	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
 	digest_size = be16_to_cpu(out->digest_size);
-	if (digest_size > sizeof(digest_struct->digest)) {
+	if ((digest_size_ptr && digest_size > sizeof(digest_struct->digest)) ||
+	    (!digest_size_ptr && digest_size != expected_digest_size)) {
 		rc = -EINVAL;
 		goto out;
 	}
-- 
2.17.1


  parent reply	other threads:[~2018-10-30 15:51 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30 15:47 [PATCH v3 0/5] tpm: retrieve digest size of unknown algorithms from TPM Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 1/5] tpm: change the end marker of the active_banks array to zero Roberto Sassu
2018-10-30 19:45   ` Jarkko Sakkinen
2018-10-31 14:43   ` Mimi Zohar
2018-11-01 14:42     ` Mimi Zohar
2018-11-05  8:10       ` Roberto Sassu
2018-11-05 13:02         ` Mimi Zohar
2018-11-05  8:07     ` Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 2/5] tpm: rename and export tpm2_digest and tpm2_algorithms Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 3/5] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 4/5] tpm: retrieve digest size of unknown algorithms with PCR read Roberto Sassu
2018-11-01 16:02   ` Mimi Zohar
2018-11-01 16:23     ` Mimi Zohar
2018-11-05  9:47     ` Roberto Sassu
2018-11-05 12:01       ` Jarkko Sakkinen
2018-11-05 13:09         ` Roberto Sassu
2018-11-05 14:48           ` Mimi Zohar
2018-11-05 17:13           ` Jarkko Sakkinen
2018-11-05 17:10         ` Jarkko Sakkinen
2018-10-30 15:47 ` Roberto Sassu [this message]
2018-10-30 19:52   ` [PATCH v3 5/5] tpm: ensure that output of PCR read contains the correct digest size Jarkko Sakkinen
2018-10-31  8:16     ` Roberto Sassu
2018-11-01 14:32       ` Jarkko Sakkinen
2018-11-01 16:52   ` Mimi Zohar

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